This invention relates to a mobile phone system with a mobile telephone accounting protocol for mobile phones, and in particular to cellular phones and radio phones that are capable of moving from one transmission station to another in a communication network. In particular, the mobile telephone accounting protocol is adapted for a mobile debit phone in which the communication traffic with the service provider is minimized to expand traffic handling capacity of the service provider by accomplishing the accounting procedures within each mobile phone unit. The mobile telephone accounting protocol is similar to that described in U.S. Pat. No. 5,325,418, which is incorporated herein by reference. In the referenced patent, an accounting system is described which has particular application to a rental phone system or a controlled phone system, such as an intra-corporate system where periodic calculation of phone charges are made prior to receipt of billings from public or switched service providers. In such systems, phone call data is stored in the mobile phone unit and charges are calculated by a host processor after a dialogue is established between the host processor and the phone unit. This system requires that a communication link be established between the host processor and the mobile phone unit and may require that the phone unit be physically connected to the host processor.
Although debit systems with internal debit and credit memory for cordless phones have been previously proposed such systems do not account for the particular complexities of mobile phone systems wherein multiple service providers may be involved in a communication network and the mobile phone is allowed to move or roam across defined zones or cells within a particular service area or across multiple service areas. In such situations, the location of the mobile phone making the call is as important for billing calculations as the location of the phone or stations being called. This added complexity complicates billing procedures for mobile phones and increases the communication session required for remote debit systems, thereby adding to airway traffic.
In addition to the objective of eliminating an accounting session with a service provider for each call made, the mobile phone with internal accounting capabilities greatly expands the potential customer base by enabling persons with inadequate credit to obtain mobile phone service by the use of a pay-as-you-go debit account. In this case, the credit risk is avoided by prepayment of service and call charges, and where credit is extended permits the credit to be provided by an entity other than the service provider, for example by the seller of the phone, or by a billing service that provides credit or pre-paid accounts for mobile phone users.
The mobile phone unit of this invention can be used with a mobile phone rental system as described in reference U.S. Pat. No. 5,325,418. Because the mobile phone unit itself includes the accounting capabilities, the rental system can be greatly expanded, allowing the return station to have minimum system hardware, and indeed, requiring only the ordinary equipment necessary to clear an account, collect the charges and store the returned phone for pick-up or return to an initiating station. The mobile phone unit itself calculates the charges on the fly and provides a cumulative account record for review at the return station. The mobile phone system of this invention is adapted for analog or digital cellular telephones, radiophones in personal communication service networks (PCS's) and other wireless communication systems where it is desirable that call accounting be done on the fly.